This is a method for the tidyr::expand generics. It doesn't sort the result explicitly, so the order might be different to what expand() returns for data frames.

expand.tbl_lazy(data, ..., .name_repair = "check_unique")



A lazy data frame backed by a database query.


Specification of columns to expand. See tidyr::expand for more details.


Treatment of problematic column names:

  • "minimal": No name repair or checks, beyond basic existence,

  • "unique": Make sure names are unique and not empty,

  • "check_unique": (default value), no name repair, but check they are unique,

  • "universal": Make the names unique and syntactic

  • a function: apply custom name repair (e.g., .name_repair = make.names for names in the style of base R).

  • A purrr-style anonymous function, see rlang::as_function()

This argument is passed on as repair to vctrs::vec_as_names(). See there for more details on these terms and the strategies used to enforce them.


Another tbl_lazy. Use show_query() to see the generated query, and use collect() to execute the query and return data to R.


if (require("tidyr", quietly = TRUE)) { fruits <- memdb_frame( type = c("apple", "orange", "apple", "orange", "orange", "orange"), year = c(2010, 2010, 2012, 2010, 2010, 2012), size = c("XS", "S", "M", "S", "S", "M"), weights = rnorm(6) ) # All possible combinations --------------------------------------- fruits %>% expand(type) fruits %>% expand(type, size) # Only combinations that already appear in the data --------------- fruits %>% expand(nesting(type, size)) }
#> # Source: lazy query [?? x 2] #> # Database: sqlite 3.34.1 [:memory:] #> type size #> <chr> <chr> #> 1 apple XS #> 2 orange S #> 3 apple M #> 4 orange M